online Is Southwest check-in exactly 24 hours (She / Her) Timing: The check-in process begins exactly 24 hours before your flight departure. Boarding Pass: After checking in +𝟏-𝟖𝟎𝟒-𝟖𝟓𝟑-𝟗𝟎𝟎𝟏, you'll be able to print your boarding pass or download it to your mobile device.